The present invention relates to (a) an electronic device manufacturing method and an electronic device which eliminates waste of materials and unnecessary manufacturing processes, and (b) a resin filling method in which a target region enveloping electronic parts is filled with a resin.
In the past, there has been a rapid spread of compact electronic devices in which a plurality of electronic parts are mounted on a substrate. Electronic devices of this type include devices which are sealed or molded by means of a resin as in the case of ICs and hybrid modules, or the like. Electronic devices of this type also includes devices which are accommodated in a metal case or in which the electronic parts are covered by a metal case.
In the manufacture of such electronic devices, substrates have been prepared for individual electronic devices, and electronic parts have been mounted on these substrates, after which sealing or molding using a resin, or the mounting of a metal case, had been performed.
The following problems are encountered in manufacturing the above-mentioned electronic devices.
First of all, in the case of devices that are resin-sealed or molded by means of a resin, since there are indentations and projections on the surfaces of the electronic devices, the electronic devices may fall from the suction chucking machine and suction chucking is difficult to accomplish when the devices are mounted on motherboards using a suction chucking type automatic mounting machine.
Secondly, in the case of electronic devices that use a metal case, although such devices are superior in that they can be shielded from electromagnetic fields and the electronic parts on the substrate can be protected, a process in which metal cases are mounted on the individual substrates is required, and this is an obstacle to the reduction of manufacturing costs.
Thirdly, since compact substrates are formed for individual electronic devices, and the work of mounting electronic parts on these substrates is automated using machinery, extra parts must be provided in order to fasten the individual substrates in place during shipping and part mounting operations, so that a waste of substrate material is generated. Such extra parts used to fasten individual substrates in place are generally called xe2x80x9cfastening partsxe2x80x9d or xe2x80x9cearsxe2x80x9d by persons familiar with the art. The electronic devices are ultimately shipped as finished products after these xe2x80x9cfastening partsxe2x80x9d or xe2x80x9cearsxe2x80x9d have been cut off and discarded.
Fourth, it is extremely difficult to accomplish resin sealing of a single electronic part mounted on a substrate in isolation from the area surrounding said electronic part. In the past, therefore, considering ease of manufacturing, the entire electronic part has been resin-sealed, or resin sealing has been performed with the electronic parts surrounding the target electronic part included, even in cases where only a single electronic part requires resin sealing. This has resulted in a waste of sealing resin.
In light of the above problems, the object of the present invention is to provide an electronic device manufacturing method and an electronic device which make it possible to (1) reduce the waste of materials, (2) reduce the number of manufacturing steps, and (3) limit resin sealing to a specified target region.
A. In order to achieve the above-mentioned objects, the present invention proposes a method for manufacturing an electronic device which has a substrate, electronic parts that are mounted on the main surface of said substrate, and a resin part that is formed on the main surface of the aforementioned substrate so that said resin part fills a specified space surrounding at least one electronic part, said electronic device manufacturing method comprising a step in which a collective substrate consisting of a plurality of substrates linked in the form of a matrix is formed, a step in which electronic parts are mounted on the main surface of the aforementioned collective substrate, a step in which the aforementioned resin part which is solidified so that it covers the aforementioned electronic parts is formed on the main surface of the collective substrate on which the aforementioned electronic parts have been mounted, and a step in which the collective substrate on which the aforementioned resin part has been formed is separated into individual substrates.
B. Additional benefits can be obtained by adding to the method described in the previous paragraph a step in which terminal electrode members are conductively connected and mounted across specified adjacent substrates on the upper surface of the collective substrate prior to the formation of the aforementioned resin part, so that these terminal electrode members cross the boundary lines of the adjacent substrates. The aforementioned resin part is formed to a specified thickness over the entire main surface of the collective substrate during the step in which the resin part is formed, and the terminal electrode members are cut in the step in which the collective substrate on which the aforementioned resin part has been formed is separated into individual substrates.
C. The aforementioned terminal electrode members are cut in the step in which the aforementioned collective substrate is separated into individual substrates; accordingly, the cut surfaces of the terminal electrode members are exposed at the cut surfaces of the aforementioned resin part, so that the terminal electrode members can be used as terminal electrodes. As a result, working of the terminal electrodes can easily be accomplished, and electronic devices manufactured by this method can be mounted with the side surfaces of said devices, i.e., the aforementioned cut surfaces, facing the motherboard. In addition, an intermediate layer consisting of an insulating elastic material can be formed on the main surface of the collective substrate (on which the aforementioned electronic parts have been mounted) prior to the formation of the resin part, so that said intermediate layer covers the electronic parts. This intermediate layer alleviates stresses generated by thermal expansion. Differences in the thermal expansion coefficients of the substrate, solder and resin part are alleviated by the intermediate layer.
D. Furthermore, in the methods described above, it is possible to use a vacuum printing method to form the resin part, so that a resin part having a specified thickness is formed over the entire main surface of the collective substrate. The use of a vacuum printing method allows formation of a resin part without any gaps around the electronic parts. Vacuum printing can be accomplished, for example, using Vacuum Printing Encapsulation Systems such as are available from Japan Rec. Co. LTD. of Takatsuki-shi, Osaka, Japan.
E. Furthermore, it is possible to dispose a resin in a vacuum state in a region which includes at least one of the aforementioned electronic parts on the main surface of the aforementioned substrate and a specified space surrounding said electronic part, in isolation from other regions, and a step in which a further resin layer is subsequently formed on the surface of the aforementioned resin part in either a non-vacuum state or vacuum state. The further resin layer is formed on the surface of the resin part which, having been formed using a vacuum printing method, is evened out. Electronic devices manufactured in this way can easily be mounted on a motherboard using a suction chucking type automatic mounting machine.
F. An additional step can be added to the methods discussed above in which at least one layer selected from a set consisting of a heat-dissipating layer, an electromagnetic field shielding layer and a metal layer is formed in a specified region on the surface of the resin part following the formation of the resin part. The electromagnetic field shielding layer or metal layer formed on the surface of the resin part blocks electromagnetic fields. Accordingly, the formation of an electromagnetic field shielding film can easily be accomplished. Furthermore, the aforementioned electromagnetic field shielding film also shows an effect in EMC countermeasures. Moreover, the heat transmitted through thermally conductive members is transmitted to the heat-dissipating layer or metal layer, and is efficiently dissipated in accordance with the surface area of this layer, so that an electronic device with a high heat-dissipating effect can easily be manufactured.
G. Furthermore, the electromagnetic field shielding layer can be formed using a resin in which at least one substance selected from a set consisting of a ferrite filler and a metal filler is dispersed. Accordingly, the electromagnetic field shielding layer can easily be formed.
H. Furthermore, the resin part can be formed using an insulating resin.
I. Furthermore, the resin part can be formed using a resin in which at least one substance selected from a set consisting of a ferrite filler and a metal filler is dispersed. This allows the resin part itself to become an electromagnetic field shielding layer.
J. Furthermore, the resin part can be formed using a material that has waterproof properties. This allows a wet-type cutting device to be used in the process in which the collective substrate is separated into individual substrate units.
K. Furthermore, when manufacturing an electronic device according to the present invention, the resin part of a specified thickness can be formed over the entire main surface of the collective substrate in the step in which the resin part is formed, and the collective substrate can be cut using a dicing device in the process in which the collective substrate on which the resin part has been formed is separated into individual substrates. The use of a dicing machine allows cutting to be accomplished very simply and with clean cut surfaces.
L. Furthermore, according to the present invention, an electronic device is proposed which comprises a substrate, electronic parts that are mounted on the main surface of said substrate, a resin part that is formed on the main surface of the aforementioned substrate so that said resin part fills a specified space surrounding the aforementioned electronic parts, and terminal electrodes that are exposed to the outside. This electronic device can be easily manufactured using a collective substrate in which a plurality of substrates on which electronic parts protected by a resin are connected in the form of a matrix.
M. The proposed electronic device can have an intermediate layer consisting of an insulating elastic material which is formed on the main surface of the substrate so that said intermediate layer fills a specified space surrounding the electronic parts. In this electronic device, stresses generated by thermal expansion and differences in the thermal expansion coefficients of the aforementioned substrate, solder and resin part are alleviated by the elastic material constituting the intermediate layer.
N. Furthermore, the proposed electronic device can have a substrate in the shape of a rectangular solid with a specified thickness. If the substrate has the shape of a rectangular solid with a specified thickness, manufacture using a matrix-form collective substrate can be easily accomplished.
O. Furthermore, in the proposed electronic device, the resin part can have the shape of a rectangular solid that is formed to a specified thickness over the entire main surface of the substrate, where the side surfaces of the resin part are positioned in the same planes as the side surfaces of the substrate. This allows the electric device to be mounted with the side surfaces of the substrate and resin part facing the motherboard.
P. Furthermore, in the proposed electronic device the resin part can have the shape of a rectangular solid formed over the entire main surface of the substrate, the terminal electrodes can be embedded in the resin part, and the end surfaces of said terminal electrodes can be exposed in the same plane as at least one of the side surfaces of the resin part and/or surface of the resin part that is parallel to the main surface of the substrate. If the terminal electrodes are exposed at the side surfaces, surface mounting with the side surfaces facing the motherboard can easily be accomplished, and the direction of mounting can easily be confirmed as a result of the exposed positions of the terminal electrodes. Furthermore, if the terminal electrodes are exposed at the surface that is parallel to the main surface of the substrate, the electric device can be mounted on or connected to a connector, or the like.
Q. Furthermore, in the proposed electronic device the resin part can consist of a resin in which at least one substance selected from a set consisting of a ferrite filler and a metal filler is dispersed. In this electronic device, the resin layer can be formed easily and in the desired shape at the time of manufacture; furthermore, the resin part has a heat-dissipating function and an electrostatic shielding or electromagnetic shielding function. Furthermore, in the proposed electronic device the resin part can consist of a resin which has at least one type of property selected from a set consisting of insulating properties, heat resistance, waterproof properties and chemical resistance.
R. In this electronic device, in cases where an insulating resin is used in the resin part, the main surface of the substrate and the electronic parts can be insulated from each other, and in cases where a heat-resistant resin is used in the resin part, the electronic parts can be protected from external heat. In cases where a waterproof resin is used in the resin part, the adhesion of moisture to the electronic parts is prevented by the resin part, and in cases where a chemical-resistant resin, e. g., an alkali-resistant, acid-resistant or corrosion-resistant resin, is used in the resin part, the electronic parts are protected by the resin part when such chemicals adhere to the electronic parts.
S. Furthermore, in the proposed electronic device at least one layer selected from a set consisting of an electromagnetic field shielding layer, a heat-dissipating layer and a metal layer can be formed in a specified region on the surface of the resin part. If this is done, electromagnetic fields are blocked by the above-mentioned electromagnetic field shielding layer or metal layer, and heat generated by the electronic parts can be efficiently dissipated by the above-mentioned heat-dissipating layer or metal layer.
T. Furthermore, according to the present invention, a resin filling method is proposed in which a specified space around electronic parts mounted on the main surface of a substrate, or the surface of an intermediate layer, is filled with a resin. This resin filling method is characterized by the fact that after at least the area around the aforementioned electronic parts is set in a vacuum state, a resin which possesses viscosity is disposed so that said resin envelops the electronic parts in the aforementioned region place. The resin is disposed so that it contacts the main surface of the substrate or surface of the intermediate layer at least in the area surrounding the aforementioned electronic parts. Then the aforementioned vacuum state is then released so that a non-vacuum state results. In this resin filling method, even if a gap should occur between the aforementioned electronic parts and the resin or between the electronic parts and the main surface of the substrate in a state in which the resin is disposed in the area surrounding the electronic parts, the interior of this gap is in a vacuum state. Accordingly, when the space outside the aforementioned resin which is in a vacuum state is placed in a non-vacuum state, the aforementioned gap will be filled with the resin as a result of the air pressure.